Investigation of Potential Saltwater Intrusion Pathways in a Fractured Aquifer using an Integrated Geophysical, Geological and Geochemical Approach
Bibliographic record
Abstract
Borehole geophysics and horizontal loop electromagnetic profiling (Max-Min) were integrated with regional and site-scale geological and geochemical data to investigate the occurrence of, and possible pathways for, saltwater intrusion near fracture zones on a small island in British Columbia, Canada. An island-wide geochemical study identified a number of coastal wells that are contaminated by seawater; however, the occurrence of high salinity groundwater is spatially irregular due to variable fracturing of the bedrock. To investigate the influence of fracturing on the presence of high salinity groundwaters, geophysical investigations were undertaken at several sites. The nature of the bedrock permeability at these sites, with respect to lithology and fracture zone proximity, is described from geologic and hydrogeologic investigations and supported using surface EM profiling. Fractures and bedding contacts within boreholes, which were suspected to dominate bedrock permeability on the basis of outcrop studies, were identified using borehole video camera in conjunction with normal resistivity, spontaneous potential and natural gamma logs. Flow meter logs, acquired under a variety of aquifer stress conditions including static, tidal and pumping are used to identify potential water transmitting fractures and the locations of entry points for fresh and saline groundwater. The low flow rates measured under the various stress conditions confirm that groundwater flow is minimal and is restricted to mudstone units and single, generally sub-vertical fractures. The low natural groundwater discharge rates near the coast, even at close distances to fracture zones, may be key to the occurrence of saltwater intrusion on many parts of the island.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".